Control unit and method for controlling a local distribution system's outtake of heat or cold from a thermal energy distribution grid

Abstract

A method for controlling a local distribution system's outtake of heat or cold from a thermal energy distribution grid. The method includes determining a base steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid, receiving a control signal indicative of reducing the steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid; determining a reduced steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid based on the control signal and the base steering temperature; determining a return temperature of a heat transfer fluid in the return, and upon the determined reduced steering temperature being lower than the return temperature, determining a temporary steering temperature higher than the return temperature and lower than the base steering temperature; and controlling the local distribution system's heat outtake based on the temporary steering temperature.

The invention claimed is: 
     
       1. A method for controlling a local distribution system's outtake of heat from a thermal energy distribution grid, wherein the local distribution system comprises:
 a device for exchange of thermal energy between the local distribution system and the thermal energy distribution grid, 
 one or more thermal energy distribution devices, 
 a feed for feeding the one or more thermal energy distribution devices with thermal energy from the device for exchange of thermal energy by conducting a heat transfer fluid, and 
 a return for returning the heat transfer fluid from the one or more thermal energy distribution devices to the device for exchange of thermal energy, the method comprising: 
 determining a base steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid; 
 receiving, at the local distribution system, a control signal indicative of reducing a steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid; 
 determining a reduced steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid based on the control signal and the base steering temperature; 
 determining a return temperature of the heat transfer fluid in the return, 
 upon the determined reduced steering temperature being lower than the return temperature, determining a temporary steering temperature being higher than the return temperature and lower than the base steering temperature; and 
 controlling the local distribution system's outtake of heat from the thermal energy distribution grid based on the temporary steering temperature. 
 
     
     
       2. The method according to  claim 1 , further comprising:
 over time determining the return temperature, and 
 gradually decreasing the temporary steering temperature while maintaining the temporary steering temperature greater than the return temperature, until the temporary steering temperature reaches the reduced steering temperature. 
 
     
     
       3. The method according to  claim 2 , wherein the gradually decreasing of the temporary steering temperature comprises:
 until the temporary steering temperature reaches the reduced steering temperature, 
 over time determining the return temperature, and 
 in response to the determined return temperature reaching the temporary steering temperature,
 determining the return temperature of the return of heat transfer fluid in the local distribution system, and 
 determining a new temporary steering temperature being higher than the determined return temperature and lower than a previous temporary steering temperature. 
 
 
     
     
       4. The method according to  claim 1 , further comprising;
 determining a temperature outside a building in which the local distribution system is arranged; 
 wherein the determining of the base steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid is based on the determined temperature outside the building. 
 
     
     
       5. The method according to  claim 1 , further comprising:
 over time determining the return temperature, and 
 gradually increasing the temporary steering temperature while maintaining the temporary steering temperature lower than the return temperature, until the temporary steering temperature reaches an increased steering temperature. 
 
     
     
       6. The method according to  claim 2 , wherein gradually increasing of the temporary steering temperature comprises:
 until the temporary steering temperature reaches an increased steering temperature, 
 over time determining the return temperature, and 
 in response to the determined return temperature reaching the temporary steering temperature,
 determining the return temperature of the return of heat transfer fluid in the local distribution system, and 
 determining a new temporary steering temperature being lower than the determined return temperature and higher than a previous temporary steering temperature. 
 
 
     
     
       7. The method according to  claim 1 , further comprising:
 determining a temperature inside a building in which the local distribution system is arranged; 
 wherein the determining of the base steering temperature for the local distribution system's outtake of cold from the thermal energy distribution grid is based on the determined temperature outside the building. 
 
     
     
       8. A controller to control a local distribution system's outtake of heat from a thermal energy distribution grid, wherein the local distribution system comprises a device for exchange of thermal energy between the local distribution system and the thermal energy distribution grid, one or more thermal energy distribution devices, a feed for feeding the one or more thermal energy distribution devices with thermal energy from the device for exchange of thermal energy by conducting a heat transfer fluid, and a return for returning the heat transfer fluid from the one or more diet mal energy distribution devices to the device for exchange of thermal energy, the controller comprising:
 a first receiver configured to receive data pertaining to a base steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid; 
 a second receiver configured to receive a control signal indicative of reducing a steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid; 
 a third receiver configured to receive data pertaining to a return temperature of the heat transfer fluid in the return; and 
 a steering temperature controller to control the steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid as the steering temperature controller is configured to: 
 determine a reduced steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid based on the control signal and the base steering temperature, 
 compare the reduced steering temperature and the return temperature, 
 upon the determined reduced steering temperature being lower than the return temperature, determine a temporary steering temperature being higher than the return temperature and lower than the base steering temperature, 
 set the temporary steering temperature as the steering temperature for the local distribution system's outtake of heat from the thermal energy distribution grid, and 
 control the local distribution system's outtake of heat from the thermal energy distribution grid based on the temporary steering temperature.